Match Between Process Waste Heat And Cold Capacity Supplied By Absorption Refrigeration

Improving energy efficiency has become an ineviTable requirement for energy conservation and emissions reduction because of the traditional energy depletion and serious environment problems.It is of great significance to research waste heat recovery and utilization technology as China has a low energy efficiency in industrial production and there is a lot of industrial waste heat directly discarded in all forms,which cause huge waste of energy.Because of good performance on energy conservation and emission reduction,absorption refrigeration technology has become an important technology of waste heat recovery and utilization.While a large number of research mainly focused on the optimization of working medium,the development of new cycle,the optimization of operation parameters and the application of typical waste heat refrigeration cycle,rather than giving in-depth study whether the match between the waste heat level and refrigeration level is reasonable.In this thesis,the model of one effect LiBr-H₂ O absorption refrigeration cycle is established and simulated by means of the process simulation software Aspen Plus.The energy level theory is employed to analyze the absorption refrigeration cycle,in order to reveal the law of energy quality change during the process of recovering waste heat into cold energy,to evaluate whether the match between the source and sink energy level is reasonable,to research the factors that affect energy level match,and to put forward the optimal match scheme.The results indicate that energy level theory is an effective thermodynamic analysis tools,which can directly and effectively reveal the law of energy quality change during the energy conversion process,and can clearly reflect the system exergy loss section and the effect of improving measures.The results also show that the refrigerating capacity of the cycle,the system exergy loss and the coefficient of the performance（COP）increase with the increase of evaporation temperature.In contrast,the system cold exergy output and the exergy efficiency decrease.The difference of system input and output energy levels is enlarged at the same time.There exists contradiction between the quality and quantity of the various levels of cold capacity from the absorption refrigeration cycle at the same heat source.The increase in the quantity of the cold capacity means the decrease in the quality.In addition,the heating load and exergy input of the system,the cold capacity,exergy loss,exergy output of the system increase with the rising of the heat source temperature.The COP of the system sharply increases first as the heat source temperature rise,then increase slowly.The system exergy efficiency rise rapidly first as the heat source temperature rise and then gradually reduce,and the difference of system input and output energy level is enlarged.Thus heat source temperature has a optimal value.At a case of a certain heat source temperature and cold capacity level,the COP of the system and the system exergy efficiency can be improved simultaneously through enhancing the efficiency of the solution heat exchanger,increasing solution concentration,and reducing the condensation temperature of the condenser.